Bonny the big clue is in the name "Nitre" this being Nitrate and many Nitrate salts will work though the common one's are Potassium or Sodium Nitrate. They can be used as purchased but there is one big drawback if you spill any of these pure hot melted oxidising salts on to any thing other than stone brick or concreate it will burst in to flame that also includes your good self. Some mixtures have other salts added to reduce the bursting into flame like Sodium Hydroxide, Sodium Chlorate if it is spilt, but they will not stop the 3rd degree burns you will have if you spill the hot salts on yourself. Just like to say that Sodium and Potassium Nitrate also Sodium Chlorate are used in the manufacture of DIY explosives and you do live in a country that asking for such things in a Chemist's shop could raise more than an eyebrow if you get my meaning. Best try Garden or Farm supply companies rather than your local Chemist
